Protein shape change ensures pick-up in right places

10 August 2010

Research has shown the complex molecular rearrangement that ensures a key cell membrane transport machine binds only to cargo proteins when in the correct environment.

The discovery furthers our understanding of how membrane-embedded proteins are transported between cell membranes in vesicles, a process vital for cell signalling, homeostasis and cell–environment interactions. 'Pinching off' a small portion of any membrane produces a vesicle, many of which become coated with a scaffold made of the protein clathrin. Adaptors link the clathrin to the membrane and select which proteins are included into the vesicle as cargo.

Researchers from the Cambridge Institute for Medical Research have found that the one of the most abundant adaptors, AP2, changes its structure radically when binding its cargo. This change unblocks AP2's two cargo interaction sites and, at the same time, puts them on the same plane as AP2's membrane binding sites so that all the sites can be used simultaneously.

Image: Depiction of cell membrane with different receptor types. Credit: Medical Art Service, Munich. Wellcome Images

Reference

Jackson LP et al. A large-scale conformational change couples membrane recruitment to cargo binding in the AP2 clathrin adaptor complex. Cell 2010;141(7):1220-9.